Even before Amazon.com Inc. put a supermarket chain in its cart, U.S. grocery delivery services were racing to grab hold of new regions, spending millions to gain a larger share of the fast-growing market.

Now, with the e-commerce giant planning to buy Whole Foods Market Inc. for $13.7 billion, giving it a large foothold in the food retail industry, the stakes are all the higher for companies such as Instacart Inc., Peapod LLC, Shipt...

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Amazon-Whole Foods Deal: 3 Things to Know

Amazon's $13.7 billion acquisition of Whole Foods Market makes the online retailer a major player in the grocery sector. WSJ's Tanya Rivero outlines three things to know about the deal. Photo: Zuma Press